Like many posts on Twitter, at the time it probably seemed like a harmless joke. In June last year, the high-profile Egyptian billionaire Naguib Sawiris – the country's richest man - posted a picture of Mickey and Minnie Mouse dressed as conservative Muslims, provoking a storm of protest from critics accusing him of denigrating Islam.

But yesterday it came back to haunt Mr Sawiris. Following the processing of a formal complaint, the prominent Christian businessman-turned-politician – who has developed numerous enemies among Egypt's swelling ranks of political Islamists – will now face a blasphemy trial over the images.

The complaint was brought by a group of about 20 lawyers, despite Mr Sawiris apologising for the incident after the images appeared.

After the post, which featured a bearded Mickey and his niqab-wearing girlfriend, he tweeted: "I apologise for those who don't take this as a joke, I just thought it was a funny picture; no disrespect meant. I am sorry."

Yet the backtracking did nothing to quell the anger of thousands of Egyptians who flocked to social networking sites to condemn him.

Mr Sawiris, who is estimated by Forbes to be worth around £2.3bn, was also the victim of a boycott campaign following the incident, with Salafi organisations urging Egyptians to avoid his telecoms companies.

"I hope the court case will stop Sawiris' ugly work," said Mahmood Fathy, president of the Salafi Al-Fadila Party.

The tycoon, whose Free Egyptians Party was trounced by the Islamist opposition in the recent parliamentary elections, is no stranger to controversy. Last summer he said that religious political forces were "hijacking" the Egyptian uprising.